Methods of forming a conductive transparent oxide film layer for use in a cadmium telluride based thin film photovoltaic device

Abstract

Methods are generally provided for forming a conductive oxide layer on a substrate. In one particular embodiment, the method can include sputtering a transparent conductive oxide layer (e.g., including cadmium stannate) on a substrate from a target in a sputtering atmosphere comprising cadmium. The transparent conductive oxide layer can be sputtered at a sputtering temperature greater of about 100° C. to about 600° C. Methods are also generally provided for manufacturing a cadmium telluride based thin film photovoltaic device.

1. A method for forming a conductive oxide layer on a substrate, the method comprising:
 sputtering a ceramic target to deposit a transparent conductive oxide layer on a substrate, the ceramic target comprising cadmium, tin, and oxygen, wherein cadmium is present in the ceramic target in a stoichiometric amount that is greater than a standard stoichiometric amount of cadmium stannate, wherein the transparent conductive oxide layer is deposited at a sputtering temperature of about 100° C. to about 600° C. 
 
     
     
       2. The method as in  claim 1 , wherein the ceramic target comprises:
   Cd 2 SnO 4   +x CdO+ y CdS 
 
       where x is 0 to about 10, y is 0 to about 10, and (x+y) is greater than 0 to about 10. 
     
     
       3. The method as in  claim 2 , wherein x is 0 to about 8, y is 0 to about 8, and (x+y) is about 2 to about 8. 
     
     
       4. The method as in  claim 2 , wherein the transparent conductive oxide layer is deposited in a sputtering atmosphere comprising an inert gas. 
     
     
       5. The method as in  claim 4 , wherein the sputtering atmosphere further comprises oxygen. 
     
     
       6. The method as in  claim 1 , wherein the ceramic target comprises:
   Cd 2 SnO 4   +x CdO 
 
       where x is greater than 0 to about 10. 
     
     
       7. The method as in  claim 6 , wherein x is about 2 to about 8. 
     
     
       8. The method as in  claim 1 , wherein the ceramic target comprises:
   Cd 2 SnO 4   +y CdS 
 
       where y is greater than 0 to about 10. 
     
     
       9. The method as in  claim 8 , wherein y is about 2 to about 8. 
     
     
       10. The method as in  claim 1 , wherein the sputtering atmosphere has a pressure from about 1 mTorr to about 100 mTorr. 
     
     
       11. The method as in  claim 1 , wherein the sputtering temperature is from about 150° C. to about 500° C. 
     
     
       12. A method for forming a conductive oxide layer on a substrate, the method comprising:
 sputtering a metal target to deposit a transparent conductive oxide layer on a substrate, wherein the transparent conductive oxide layer is deposited at a sputtering temperature of about 100° C. to about 600° C., wherein the metal target consists essentially of cadmium and tin according to the formula: Cd x Sn, wherein x is 4 to 10. 
 
     
     
       13. The method as in  claim 12 , wherein the transparent conductive oxide layer is deposited in a sputtering atmosphere comprising oxygen. 
     
     
       14. The method as in  claim 12 , wherein the sputtering temperature is from about 150° C. to about 500° C. 
     
     
       15. The method as in  claim 12 , further comprising:
 forming a resistive transparent buffer layer over the transparent conductive oxide layer; 
 forming a cadmium sulfide layer over the resistive transparent layer; and, 
 forming a cadmium telluride layer over the cadmium sulfide layer. 
 
     
     
       16. A method for manufacturing a cadmium telluride based thin film photovoltaic device, the method comprising:
 sputtering a ceramic target to deposit a transparent conductive oxide layer on a substrate, the ceramic target comprising cadmium, tin, and oxygen, wherein cadmium is present in the ceramic target in a stoichiometric amount that is greater than a standard stoichiometric amount of cadmium stannate, wherein the transparent conductive oxide layer is deposited at a sputtering temperature of about 100° C. to about 600° C.; 
 forming a resistive transparent buffer layer over the transparent conductive oxide layer; 
 forming a cadmium sulfide layer over the resistive transparent layer; and, 
 forming a cadmium telluride layer over the cadmium sulfide layer. 
 
     
     
       17. The method as in  claim 16 , wherein the target is a ceramic target comprises:
   Cd 2 SnO 4   +x CdO+ y CdS 
 
       where x is 0 to about 10, y is 0 to about 10, and (x+y) is greater than 0 to about 10. 
     
     
       18. The method as in  claim 16 , wherein the target is a ceramic target comprising:
   Cd 2 SnO 4   +x CdO 
 
       where x is greater than 0 to about 10. 
     
     
       19. The method as iii  claim 16 , wherein the target is a ceramic target comprising:
   Cd 2 SnO 4   +y CdS 
 
       where y is greater than 0 to about 10.